PLASTIC

Plastic can sometimes be a convincing gem imitation, like the pink plastic in this butterfly brooch.

Species:  Plastic
​​Mohs Hardness:  3 to 4 out of 10
Color:  Can be any color.
RI:  1.460 to 1.700
Birefringence:  None
SR/DR/AGG:  SR, commonly with strong ADR due to strain
Spectrum:  Not diagnostic
Fluorescence:  Not diagnostic
SG:  1.05 to 1.55

Plastic Facts

Plastic used to be the standard material for watch crystals, even for luxury brands like Rolex.

Plastic can be produced in nearly every color.

Plastic has a very light heft.

Colorful plastic molds are used in costume jewelry pieces, as they are able to be mass produced quickly, and cost-efficiently.